Aluminosilicate coating prepared by low pressure chemical vapour deposition using TEOS and AlCl 3 as precursors

Aluminosilicate coating was prepared by low pressure chemical vapour deposition using tetraethoxysilane and Al trichloride as precursors at temperature in the range of 300–850°C. The effect of the deposition temperature on deposition rate was studied by weight gain of a graphite substrate before and after deposition. The chemical composition and phase identification of the coating were confirmed by EDS and XRD. The morphology of the surface of the coating was observed by SEM. The optimal deposition temperature was 600°C which was lower than the optimal temperature of SiO₂ deposition. Both an esterlysis reaction and a hydrolysis reaction must take place between tetraethoxysilane and Al trichloride during deposition. The dense aluminosilicate coating composed of the crystalline γ-Al₂O₃ and amorphous compound of Al₂O₃ with SiO₂.